We propose a tool for evaluating the functional impact of headaches that uses computerized adaptive testing (CAT) to achieve more practical and more precise assessments by matching the questions to each patient's headache severity level. In previous work, we developed a headache impact item bank that improved score precision and validity and provided measurement over a wider range, and we developed cross-calibration procedures that allowed us to directly compare results from CAT and existing headache scales. Items were administered using Dynamic Health Assessment (DYNHA[unreadable]) software to reduce response burden. In Phase I, we developed and piloted a prototype assessment (HEADACHE-CAT) that combines a static generic health- related quality of life (HRQOL) tool with an enhanced headache impact CAT which draws upon an expanded item bank. Results from a pilot test of the HEADACHE-CAT showed that measurement precision and efficiency increased with the larger item bank. Patient participants provided positive feedback on the HEADACHE-CAT and a prototype patient report that guides interpretation of generic HRQOL and headache impact results. The aims for Phase II are to: (1) improve the content validity of the HEADACHE-CAT by enhanced item selection procedures; (2) improve practical usefulness of the HEADACHE-CAT by heuristic evaluation and usability testing; (3) evaluate the responsiveness of the HEADACHE-CAT to changes in the clinical condition over time; (4) develop and evaluate item administation with voice activation for greater accessibility to patients with visual or literacy impairments and evaluate the effects of survey length on patient satisfaction; and (5) finalize a single comprehensive HEADACHE-CAT assessment system that: a) uses item banks for generic HRQOL and headache impact domains, b) has a comprehensive user guide, c) can provide scores in the metric of traditional scales, d) can deliver individual patient and clinician reports, and aggregate-level reports for providers to improve group-level assessment and monitoring efforts. The HEADACHE-CAT assessment tool developed by this project will make screening and routine outcomes monitoring of HRQOL feasible for headache sufferers by greatly lowering data collection costs, respondent burden, and increasing the breadth and precision of measurement. [unreadable] [unreadable] [unreadable]